class_docstr: A tree built by XGBoost.
docstr: Sum Hessian of a node.
docstr_tok: ["Sum","Hessian","of","a","node","."]
code: def sum_hessian(self, node_id: int) -> float:
      """Sum Hessian of a node."""
      return self.nodes[node_id].sum_hess
  
imports: import argparse
  import json
  from dataclasses import dataclass
  from enum import IntEnum, unique
  from typing import Any, Dict, List, Sequence, Union
  import numpy
label_desc: Use image node_id 3 for calling the Tree obj's underlying member method code with example usage: obj.sum_hessian(node_id) and returns: self